Digital speech communication system for minimizing quantizing noise
US4048443A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 12, 1975 |
| Grant date | Sep 13, 1977 |
| Priority date | — |
| Expiry date | Dec 12, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/667
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A digital speech communication arrangement includes apparatus for partitioning a speech signal into a plurality of nonuniformly related, preassigned intelligibility contributing subbands, and quantized with an accuracy (bit allocation) based upon perceptual criteria. As a result, the quality of the coded signal is improved over that obtained from a single full-band coding of the total spectrum. "Integer-band" sampling may be employed to alias the signal in an advantageous way before coding. Each subband portion is digitally encoded after sampling at a rate related to the bandwidth of the subband. The digital codes of the subband are combined and applied to a common communication channel. A replica of each subband is formed by separating the digital codes, producing a sampled form of each digital coded signal and selecting the subband of the speech signal from said sampled form. The subbands are combined to reconstruct the speech signal. Other features include: aliasing for efficient frequency transposition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.